Summary: The overall goal of this diversity supplement to the NIA RCMAR P30 UCSF Center for Aging in Diverse Communities (CADC) parent grant is to provide Dr. Cathy Samayoa, a Latina molecular biologist, with training in behavioral research methods to study aging and aging-related diseases, career development, and mentorship to support her transition into an independent research career focusing on biobehavioral mechanisms underlying health disparities in aging. These goals directly align with the aims of the parent P30 award and with NIA's overall mission to investigate factors impacting aging across the life course. This proposal's research goal is to investigate relationships between mental health (stress, depression) and biological markers of stress and sleep (cortisol awakening response [CAR], melatonin) to gain insight into mechanisms that contribute to accelerated biological weathering (excess biological wear and tear) and to health disparities among Latina breast cancer survivors. CAR is a measure of stress reactivity while melatonin is a sleep-related biomarker. Emerging evidence suggests these measures are contributors to health disparities for various health conditions and age-associated diseases. Even so, we lack knowledge of the impacts of these factors on one another. We propose to leverage our existing data set, collected for our Nuevo Amanecer study of rural Latina breast cancer survivors, to investigate the longitudinal and simultaneous reciprocal relationships between CAR, melatonin, and self-reported measures of mental health within this health disparity population. By investigating directional pathways and their relative strengths, we can identify and potentially target early points of intervention. The research experiences and career development activities have been carefully planned to serve as a cohesive whole to foster Dr. Samayoa's development into a multidisciplinary investigator with a biobehavioral focus. These include coursework and directed readings on aging, behavioral science methods, measurement, and statistical modeling; strengthening her publication record; participation in monthly CADC meetings; and attendance at national meetings and workshops. Finally, in year two, she will develop a K-award proposal that will further investigate how behavioral and social factors impact biological mechanisms involved in aging and health disparities among minorities.